The Temporomandibular Joint in Juvenile Idiopathic Arthritis, focusing on Quality of Life, Oral Microbiome and Intervention

The temporomandibular joint (TMJ) is commonly involved in juvenile idiopathic arthritis (JIA), and may lead to impaired mouth opening, pain and facial growth disturbances. Asymptomatic TMJ arthritis may be diagnosed late in the disease course, thus management is challenging. The overall objectives of this thesis were to provide new knowledge on quality of life (QoL), the oral microbiome and interventions in children with JIA and TMJ arthritis. Cross-sectional and observational multicenter studies were performed in addition to a systematic literature review. The present work showed lower QoL scores in children with JIA and TMJ arthritis compared to those without TMJ arthritis, and healthy controls. Clinicians should pay special attention to TMJ involvement in children with cervical spine involvement, younger age at onset, polyarticular course and longer duration of JIA. Microbiota associated with chronic inflammation in saliva is more common in JIA compared to healthy children and some of these bacteria were associated with increased disease activity in JIA. Regular dental follow-ups with special concern to oral hygiene and infections may therefore be recommended in children with JIA. Single corticosteroid injections in adolescents with JIA and TMJ arthritis may be efficient as a supplement to systemic treatment; we found reduced inflammation, slightly improved mouth opening and no side effects, but pain was not significantly reduced. Finally, surgical intervention of dentofacial deformities in patients with JIA can be recommended for improvement of TMJ function and skeletal alignment, even if the level of evidence in existing studies are low